Aim of the study: The development of preventive measures for construction workers makes analysis of the workload necessary. However, the worker’s movements change continuously according to the progress made performing the task and are mainly determined by the weight of the material handled and the restricted space in the working area. Criteria are therefore required for assessing the workload during the performance of different sequences of work. These criteria are the basis of a comparative study of different working conditions and allow quantitative analysis of the cumulative load effects on the musculo-skeletal system and the lumber spine. Methods: The study presented is based on five different professional groups: bricklayers, scaffolders, carpenters, plumbers and painters. In all, the collective analysed consisted of 340 construction workers. This survey provided a large database for the statistical analysis of the sequences of action that occur and the resulting workload. The workload of construction workers was investigated taking into consideration different construction sites, the materials handled, time pressure and work organisation. Results and Conclusions: The study gives a detailed picture of the load on the lumbar spine of the professional groups analysed. For bricklayers the load is mainly due to bent posture. Carpenters usually work in an upright position and therefore the load caused by body posture is less important, but the weights manipulated are in the range of those handled by bricklayers. Scaffolders normally carry heavy weights in an upright posture; therefore, the consideration of body posture is less important. Plumbers and painters, on the other hand, rarely manipulate heavy weights, but they are often forced to take a difficult body posture within restricted spaces. The results of the survey showed that it is possible to rank the different tasks of construction workers with respect to the load on the lumber spine. This allows preventive measures to be taken and epidemiological studies to be evaluated which consider the degeneration of the musculo-skeletal system.